On Fri, 14 Jun 2024 16:48:06 -0700 Chris Li <chrisl@xxxxxxxxxx> wrote: > This is the short term solutiolns "swap cluster order" listed > in my "Swap Abstraction" discussion slice 8 in the recent > LSF/MM conference. > > When commit 845982eb264bc "mm: swap: allow storage of all mTHP > orders" is introduced, it only allocates the mTHP swap entries > from new empty cluster list. It has a fragmentation issue > reported by Barry. > > https://lore.kernel.org/all/CAGsJ_4zAcJkuW016Cfi6wicRr8N9X+GJJhgMQdSMp+Ah+NSgNQ@xxxxxxxxxxxxxx/ > > The mTHP allocation failure rate raises to almost 100% after a few > hours in Barry's test run. > > The reason is that all the empty cluster has been exhausted while > there are planty of free swap entries to in the cluster that is > not 100% free. > > Remember the swap allocation order in the cluster. > Keep track of the per order non full cluster list for later allocation. > > This greatly improve the sucess rate of the mTHP swap allocation. > I'm having trouble understanding the overall impact of this on users. We fail the mTHP swap allocation and fall back, but things continue to operate OK? > There is some test number in the V1 thread of this series: > https://lore.kernel.org/r/20240524-swap-allocator-v1-0-47861b423b26@xxxxxxxxxx Well, please let's get the latest numbers into the latest patchset. Along with a higher-level (and quantitative) description of the user impact. I'll add this into mm-unstable now for some exposure, but at this point I'm not able to determine whether it should go in as a hotfix for 6.10-rcX.
